Combination process for producing lubricating oils



Nov. 24, 1953 F. H. BLANDING COMBINATION PROCESS FOR PRODUCINGLUBRICATING OILS Filed Sept. 50, 1950 mzON All m @NW mzoN ZOFJFQQPatented Nov'Q Z4, 1953 U'Nrrrogs srArEsf Forrest Blandng,"CranfordfNlJg', assign'oto Standard*I Oil Development Company; "a corpo-1`ratio'nfof Delaware Y.

Thls invention" concerns" a novel -vprocessvfor producing* lubricating'oils 1 of particularly f high quality.' In accordance with"thisinventiongla suitable petroleumfeed'stock-is'-subjected'to ai scatalytic cracking voperation fand-thereafter l-a 5' distillatev boilingin theV lubricating voil 'bolingl range-is separated from4'thecrackedproductie-J- This 'distillate is 'then dewaxed and fsbjeot'ed to f a solvent extraction operationto provideaparafnic'iubricatingon of remarkaiyhighviscosityf-"l0 indexfu i As i'skgenerally knownglan importantcriterion i of a' lubricating' loil`relates fto-= the Y viscosity char-f' 1'" acteristir'zs of the'oil.4'l'orfliiiany applications temperatures' 'at Which'i-f'a" lubricantmustfbe' ern-F -15 played are f several hundred degrees' i Fahrenheitabove *temperatures fexistentfprior to use of the particular mechanism.Consequently, it becomesi l a realproblern to providelubricatingoils'l'1a`,v-ing":v the -iproper viscosity Lover Y' the' `entire f-operating"20- temperatur'e'range vduetto the* decrease'lin' viscosity'iofalubricatingfoil 'as the@ oil fbecornes l heated yThis oharactristioofiaf`1ubricati`n'gf oil Ts is generallyidentiedas"the`-viscosityiindexilof the foil :malessemiauylprovidesfinfrmation as 2.5 to thechange'iniviscosity offthe 'oilovertheftem# perature range'of l'OOlto` 2109 FI -It isap'pa'r'ent that'for-many applications it'ii'sdesirableto e'mploy'lubri'c'a'ting'oilshav-ing" 'the highest possible 1 viscosity vindex.V 30

In general', threetypesof chemical 'compounds are to be found in the"lubricating oil fraction-fof ,z a crude petrioleurni-"Thesetypesofchelnical coinpounds Vare 'parainicg aromatic, andinaphthenic: 1i hydrocarbons-*It is now? known that'th'e parar'-nic'hydrocarb'ons have by farthefhighestviscosity indices." Thus,vvr'-paraffinic hydrocarbons 'i have viscosity indice's'ofabou't'l25fto"`180. 'iNaph- ATf thenie andaromatic' hydrocarbons"have"m`ateriallyrlowerviscosity' indices fand materials Elrioh 4* such"lmixed 'basecrude oils'. In particular, `it has "56 2 been"f ound"that byemplying'soiveitextraction processes,`AL lubricatingfoils maybe fmademore parafiinioby `theselective removal' of aromatic compounds'.*Howeve-the solvents which may be employedv for t"this"generalprocessfwhile being highly selective 5 for fthe "fremoval of condensedring aromaticconstituents', "are less selective for removing naphtlienicconstituents and i `one or two ring aromatic constituents." As a result,lubricating oils obtained by solventfextractiori proc-' essing arecharacterized'by containing large proportions of naphthenic compoundsandfone or two ring aromatic `compounds having'flong side chains, thuslowering the 'potential viscosity index` of the oil. K

In accordancewith thisfinvention, means have now been found forincreasing the viscosity index of lbricatingioils bynotonlyf's'electively removing aromatic hydrocarbonskbutalso byselectively removing naphthenichydrocarbons? The end re sult'is aparanic lubricating*oilcntainingA only minor proportionsofv naphtlrehicand" aromatic hydrocarbons 'andhavingI viscosity'indices approachingthose of paraiinic hydrocarbons or ap-l p'roaohing thevalue-bf 1-25f`ohigher;

The7 process by Vvvhiohtlris may bev accomplished depends-upon `a`lcombinavtionlof treating steps.' In a'rirststepV of theioperationg asuitablefeed stock'isfsubjeotedito a catalyticra'cking "operation. Thecatalytic'crackingoperation is effective to substantially eliminate`rnaphthenio hy drocarbons present'in 'the'raw feed stockt There` after,the products of tl'iezcatalytic cracking step may be subjected'to'solvent extraction operations so as to selectivelyV remove the'faromatic'constituents.

The 'generalnature of this"process may be Weil understood byreference'ito the 'accompanying' drawing referred to inl theffollowing'description of one example by which the requisite' processing 'Y may beconducted;` l l Referring now 'to the` drawing 'illustrating theentirein-tegralprocesstobe employed,numeral"-` I designatesla crudel"petroleum distillation zone. f A crude petroleum'oil such-as a'mixed'base'crude oil is introduced-to 'distillationv4 zone! through line `2.The distillationoperationis"conducted to permit removal ofvolatile'fractionsoverhead through line' 3 'andvof' heavier `rboilingproducts such as gasoline," kerosene` 'and heating" oils throughYsidestreani Withdrawals" 4; 5,1 6 and so on. Thel heavier boiling'fractions having initial' boiling'ra'ngesfof from 800`to'1'1'00'F andhigher are vvitl'idravvnas a bottoms'A product throughV- line 1. It is'particularly"contemplated that in the practice of this invention,distillation zone I be of such a nature as to provide a higher boilingfraction boiling in the range of about 70,0 to 1100" F., preferably asobtained by vacuum distillation operations. This fraction is thenconducted to a catalytic cracking zone identified by the rectangle 8.The cracking operation to be conducted in zone 8 is of any desired typeemploying a catalyst such as modified natural or synthetic clay or geltype catalysts. Examples of these are montmorillonite clays,silica-alumina, silica-magnesia composites and other conventionalcracking catalysts. The operation may be of a continuous or batch natureemploying iixed beds, moving beds, uidized, or suspensoid systems. Theheat required for cracking may be supplied as preheat of processedmaterials and/or as the sensible heat of exothermically regeneratedcatalyst or in any other conventional manner. The cracking is carriedout at temperatures of about 800 to 1000 F. and pressures of aboutatmospheric to 25 p. s. i. g. or higher in a manner well known. Thetotal cracked products are removed from cracking zone 8 and areconducted to a product fractionator 9. Fractionator 9 is operated toremove lighter fractions of the cracked products through overhead I0,side streams I I, I2 and so on. A bottoms product is obtained fromfractionator 9 which may be removed through line I4. In the event thecracking operation conducted in zone 8 was of a iiuidized nature, thematerial withdrawn through line I4 will contain a small percentage ofcatalyst particles carried over from zone 8. In this case, it isnecessary to pass the product stream of line I4 to a settler I5 orotherwise to permit separation of the liquid hydrocarbon product fromthe catalyst. Thus, a clariiied hydrocarbon stream is removed from ZoneI5 through line I6. This stream is conventionally designated asclarified cycle oil. For the purposes of this invention, the bottomsproduct of fractionator 9 corresponding to the stream of lines I4 or I6boils in the range of about 700 to 1100".

As the conduct of the process as described here tofore is generally wellknown to the art, no further description of this phase of the process isconsidered necessary. The stream of line I6 derived, as indicated, isthen conducted to suitable dewaxing facilities identified by rectangleI'I in the drawing. The operation conducted in zone I'I may be chosenfrom any of the conventional dewaxing processes of a nature to reducethe wax content of the hydrocarbon fraction treated to any desiredextent. In general, it is preferred that a solvent dewaxing operation beemployed. For example, the hydrocarbon oil of line I6 may be diltuedwith about 2 to 4 parts per volume with a solvent such as propane ormethyl ethyl ketone. The mixture of hydrocarbon oil and solvent is thenheated sufficiently to secure the solution of all wax present.Thereafter, the mixture of oil and solvent is cooled to a temperature oiabout F. to 10 F. so as to secure the crystallization of the waxpresent. The chilled mixture of oil, solvent and wax is then filtered toeliminate this wax, permitting removal from zone I'I through line I8 ofa dewaxed hydrocarbon oil.

The dewaxed oil is then passed to a solvent extraction zone I9 whereinthe oil is subjected to contact with a solvent exerting a selectivesolvent action towards aromatic constituents. It should be noted that,as described, the oil is dewaxed prior to solvent extraction. However,if desired, the dewaxing operation may follow til@ solvent extractionoperation so that, as will be seen, the raffinate of the solventextraction operation may be subjected to dewaxing.

As is well known, a variety of solvents may be employed to secure thedesired selective removal of aromatic constituents. Thus, for example.sulfur dioxide, phenol, furfural, nitrobenzene and other solvents may beemployed. While the contacting of the solvent and oil may be conductedin any desired contacting equipment of a batch or continuous nature,countercurrent treating technique is preferably employed. In such asystem, the oil feed of line I8 is introduced to a countercurrentcontacting tower I9 at a point near the bottom thereof. Tower I9 isprovided with packing, perforated plates or equivalents to secureeffective liquid-liquid contacting. A solvent such as phenol isintroduced at an upper portion of the tower as through line 20. The oilpasses upwardly through the tower while the solvent passes downwardlythrough the tower, permitting re-` moval from the bottom of the tower ofwhat is known as an extract phase through line 2 I. The extract phasewill consist principally of the solvent such as phenol together with theconstituents selectively extracted from the oil consisting principallyof aromatic hydrocarbons. The n terial withdrawn from the top of towerI9 through line 22 is known as the raiiinate phase and consistsprincipally of the initial oil feed minus the aromatic constituentsoriginally present in the feed, admixed with small proportions of thesolvent employed during the contacting. The rafiinate is preferablypassed to a iinal distillation zone 23 wherein residual solvent isdriven overhead through line 24 while the ilnal lubricating oil productis removed as a bottoms product through line 25.

As described, the process of this invention, preferably necessitates thesegregation of a crude petroleum oil into a heavy boiling fractionboiling in the range of about 700-1100 F. This fraction is thensubjected to a catalytic cracking operation operative to substantiallyeliminate naphthenic hydrocarbons from the fraction. The crackedproducts are then fractionated to provide a clear oil boiling in therange of about 700-` 1100 F. This oil is then subjected to processingeffective to selectively remove the aromatic constituents present in theoil. As indicated, this processing preferably entails contacting of theoil with a solvent selective for aromatic hydrocarbons. However, it iswithin the scope of this invention to employ equivalent operations suchas contact with an adsorbent such as silica gel which is also suitablefor selectively removing aromatic hydrocarbons. Either before or afterthe selective removal of the aromatic hydrocar bons, the oil is to besubjected to a dewaxng op eration so as to eliminate a material quantityof the Wax present in the oil.

As a specific example of the operation and utility of this invention, agas oil was subjected to a uidized catalytic cracking operation. The gasoil boiled in the range of about 650-1100 F. and was derived from amixture of West Texas and similar types of crude oil. The products ofthe catalytic cracking operation were fractionated and treated toprovide a clariiied oil boiling in the range of '70D-1100D F. rFhisclarified oil was then subjected to contact with a selective solventconsisting of phenol containing 7% of water as a solvent modifier.Contact was carried out in a contacting tower providing 7 extractionstages while injecting 2.8% of water pistoiese 'Pheitbl fetmc-tion ofcatlytic V`'cycle storie 1 l 165%' cestino foinspirant"fnphami; 218% rzoinjection, 7

l Lge Food waxy topped to 700L7 .Dcwaxed topped Yield on feed, vol.percent 100 ln spections:

l Clarified oil from a catalytic cracking operation.

2 By extrapolation from viscosity at 210 F. and 150 F.

Referring to Table I, it will be noted that inspections of the feed andthe raffinate obtained from the phenol extraction are given. Inaddition, data is presented as to the nature of the raiinate afterhaving been dewaxed in a ketone dewaxing operation reducing theraffinate to a pour point of about It is to be understood that asindicated in the table, the raffinate was fractionated so as to securethe fraction boiling in the lubricating oil boiling range of about 700to 1100 F.

It will be observed that the nal dewaxed raffinate product consisted ofa lubricating oil having a viscosity index of 106, indicating that theprocess as conducted was operative to provide a high viscosity indexlubricating oil.

In this example, the initial gas oil, subjected to cracking, had acontent of about 26% aromatics, 25% naphthenes, and 49% parainiccompounds. After cracking, the clarified oil was found to contain 67%aromatic compounds and 33% non-aromatic compounds, more than 85% of thenon-aromatic compounds being parainic in nature. tion of naphtheniccompounds achieved by the catalytic cracking. Finally, after the solventcontacting, the ramnate was again analyzed and it was found that thearomatic content had been reduced to about 12%, while the non-aromaticcontent was 88%. Two points of particular note are to be made from thisdata. First, the phenol extraction operation provided a yield of nallubricating oil of about 67% based on the nonaromatic content of the oilsubjected to phenol extraction. Secondly, the phenol extractionconducted was not carried out to the extent of conn plete aromaticremoval so that by a somewhat more severe extraction operation, greateraromatic removal could have been achieved providing a higher viscosityindex product. This was demonstrated by segregating the non-aromaticportion of the raffinate by silica gel treatment, after which it wasdetermined that this portion had a viscosity index of 119.

As a. further example to bring out the advann tages of the process ofthis invention, the following considerations are presented.

An ordinary high boiling gas oil, boiling in the range of about 700 to1100 F., may contain about 23% aromatic hydrocarbons, and 20% naphthenichydrocarbons. Such an oil has a vis cosity index of only about 65 andwould not be considered a good feed material to be subjected toprocessing for the production of high viscosity This shows thesubstantial elironai *Feed Percent treat 200 300 Yield, vol. percent 1007 6 67 61 V. I. (undewaxed) 65 95 105 110 Referring to this table, itshould be noted that the viscosity indexes given are for the undewaxedphenol treated raffinate. Depending upon the wax content of the treatedraiinate, dewaxing would lower the reported viscosity indexes by 10 to30 units. It is apparent from this data that phenol treating of such agas oil would not be attractive for the production of high qualitylubricating oil. This is particularly true since a phenol treat of about200% is the maximum percent treat employed in practical commercialoperations.

By contrast, however, if the gas oil referred to is subjected to theprocess of this invention, necessitating the catalytic cracking of thisoil and the fractionation of the portion boiling in the range of 700 to1100 F., the following phenol treating results may be obtained,employing the conditions of the preceding example:

1e l. V. I. (undewaxed) 108 It will be noted from this table that inphenol treating the catalytically cracked gas oil a much higherviscosity index product may be achieved. In this case only a 50 or 60%phenol treat is required to produce a lubricating oil having a viscosityindex of contrasted to the 300% treat required in processing the virgingas oil. In addition to this a somewhat better yield is obtained. Inview of the fact that much of the cost of a commercial plant dependsupon the extent treat applied, large savings in phenol treatment toachieve a given quality lubricating oil is thus possible.

What is claimed is:

1. The process of producing a lubricating oil comprising the steps ofcatalytically cracking a gas oil feed stock boiling in the range ofabout 650 to 1100 F., fractionating an oil fraction from the crackedproducts boiling in the range of about 700 to 1100 F., and thereaftercontacting said fraction with a selective solvent for aromatic compoundsto remove aromatic compounds from the said fraction, said processincluding the step of dewaxing the said fraction after the catalyticcracking step, whereby a high Viscosity index lubricating oil isobtained.

2. The process defined by claim 1 in which the said fraction aftertreatment with the said selec tive solvent for aromatic compounds istreatedV with silica gel.

3. 'I'he process dened by claim 1 in which the said gas oil containssubstantial portions of aromatic, naphthenic, and parainic hydrocarbons.

4. The process for producing a high viscosity index lubricating oil froma gas oil feed stock containing substantial portions of aromatic,naphthenic and paraflinio hydrocarbons and boiling in the range of about650 to 1100 F., com- 7 prsing the steps of catalytically cracking thesaid References Cited in theme of this patent gas oil, segregating aclered oil. f rom the said UNITED STATES PATENTS crackmg operatlonhaving a boiling range of t about '100 to 11oo F., and thereafterconnecting Numoef Name Date said clarified oil with about 50 to 400volume per- 5 025355 Whitely Dec- 31- 1935 cent of phenol, said processincluding the step 210701383 Tuttle Feb- 9: 1937 of dewexing the alarmedoil, whereby aromatic 2,379,966 Johnson July 10, 1945 hydrocarbons areselectively removed and a high 429,875 God et al- Oct"- 281 1947viscosity index lubricating oil is obtained. 2,448,489 Hlrschler Aug- 311943 FORREST H. BLANDING. 10

1. THE PROCESS OF PRODUCING A LUBRICATING OIL COMPRISING THE STEPS OF:CATALYTICALLY CRACKING A GAS OIL FEED STOCK BOILING IN THE RANGE OFABOUT 650* TO 1100* F., FRACTIONATING AN OIL FRACTION FROM THE CRACKEDPRODUCTS BOILING IN THE RANGE OF ABOUT 700* TO 1100* F., AND THEREAFTERCONTACTING SAID FRACTION WITH A SELECTIVE SOLVENT FOR AROMATIC COMPOUNDSTO REMOVE AROMATIC COMPOUNDS FROM THE SAID FRACTION, SAID PROCESSINCLUDING THE STEP OF DEWAXING THE SAID FRACTION AFTER THE CATALYTICCRACKING STEP, WHEREBY A HIGH VISCOSITY INDEX LUBRICATING OIL ISOBTAINED.